Increased muscular efficiency during lactation in Colombian women.
OBJECTIVE
To determine the muscular efficiency of lactating women and compare it to that of nonpregnant, nonlactating (NPNL) women.


METHODS
The study was retrospective. The subjects were selected randomly in the two groups and studied on three occasions (rounds) separated by approximately three months.


METHODS
There were 109, 101, and 80 NPNL women and 45, 31 and 16 lactating women in rounds 1, 2 and 3 respectively, 19-43 y of age, living under economically deprived conditions in Cali, Colombia, who participated in the study.


METHODS
Muscular efficiency was measured as delta efficiency on a cycle ergometer.


RESULTS
Muscular efficiency was significantly higher in lactating women in all three rounds compared to NPNL women. In six women it was possible to measure efficiency at variable times prior to their pregnancies, and again during lactation about three months post partum. There was a statistically significant (P = 0.03) increase in muscular efficiency during lactation.


CONCLUSIONS
Lactation results in about a 5% increase in muscular efficiency which may contribute to the adaptation of the mother to the increased energy demands associated with lactation.
Spurr
G B
GB
Department of Physiology, Medical College of Wisconsin, Wilwaukee 53226, USA.
Dufour
D L
DL
Reina
J C
JC
D000328:Adult; D001642:Bicycling; D015992:Body Mass Index; D001835:Body Weight; D003105:Colombia; D004734:Energy Metabolism; D016552:Ergometry; D005260:Female; D006801:Humans; D007774:Lactation / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D005082:Physical Exertion; D012189:Retrospective Studies